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List:       linux-kernel
Subject:    Re: Kernel profile
From:       tornaria () cmat ! edu ! uy (Gonzalo Tornaria)
Date:       1996-07-31 21:23:13
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DUPRE Christophe <duprec@jsp.umontreal.ca> wrote:

 > Excuse for talking before checking the code, but I think two
 > lists would be simpler and probably faster...

 > With one list, your "scavenger" need to walk the list, and when
 > it finds a non-zeroed structure, it needs to zero it then move it
 > to the front of the list. If you have two lists, scavenger only
 > takes the first of the non-zeroed list, zero it then puts it at
 > the front of the second list, no walking necessary.

 > Secondly, with only one list, you need a way to check if the
 > structure has been zeroed or not - either add a flag to the
 > structure, or re-use an already there flag... Either way, it's a
 > flag that needs to be checked then cleared when a process needs
 > to allocate a structure.

 > So the one-list solution might use a bit more memory (though not
 > much), add a flag clear, and slow down the "scavenger" in it's
 > job because it needs to walk the list.

    You can do with one list. Take zeroed structures from the head, and put used
non-zeroed structures at the end. You just need a pointer to the first
non-zeroed structure in the list, so the "scavenger" knows where to start
zeroing, and you can check whether you are out of zeroed structures. Or you can
add non-zeroed after the first non-zeroed (so you don't need a pointer to the
end).

Saludos,
Gonzalo

GM/CS/S d? a-- C++(+++) UL++(+++)>++++ P++>+++ L+++>++++ E---
W-(+) N+(++) w--- O M-(--) V-(--) PGP(--) b++(+++) G++ e>++++


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